mod_authn_dbd - Apache HTTP Server Version 2.4









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Apache HTTP Server Version 2.4



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Apache Module mod_authn_dbd

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Description:User authentication using an SQL database
Status:Extension
Module Identifier:authn_dbd_module
Source File:mod_authn_dbd.c
Compatibility:Available in Apache 2.1 and later
Summary

    This module provides authentication front-ends such as
    mod_auth_digest and mod_auth_basic
    to authenticate users by looking up users in SQL tables.
    Similar functionality is provided by, for example,
    mod_authn_file.
    This module relies on mod_dbd to specify
    the backend database driver and connection parameters, and
    manage the database connections.

    When using mod_auth_basic or
    mod_auth_digest, this module is invoked via the
    AuthBasicProvider or
    AuthDigestProvider
    with the dbd value.

Topics

 Performance and Caching
 Configuration Example
 Exposing Login Information
Directives

 AuthDBDUserPWQuery
 AuthDBDUserRealmQuery

Bugfix checklisthttpd changelogKnown issuesReport a bugSee also

AuthName
AuthType

  AuthBasicProvider


  AuthDigestProvider

DBDriver
DBDParams
Password Formats
Comments


Performance and Caching

Some users of DBD authentication in HTTPD 2.2/2.4 have reported that it
imposes a problematic load on the database.  This is most likely where
an HTML page contains hundreds of objects (e.g. images, scripts, etc)
each of which requires authentication.  Users affected (or concerned)
by this kind of problem should use mod_authn_socache
to cache credentials and take most of the load off the database.


Configuration Example

This simple example shows use of this module in the context of
the Authentication and DBD frameworks.
# mod_dbd configuration
# UPDATED to include authentication caching
DBDriver pgsql
DBDParams "dbname=apacheauth user=apache password=xxxxxx"

DBDMin  4
DBDKeep 8
DBDMax  20
DBDExptime 300

<Directory "/usr/www/myhost/private">
  # mod_authn_core and mod_auth_basic configuration
  # for mod_authn_dbd
  AuthType Basic
  AuthName "My Server"

  # To cache credentials, put socache ahead of dbd here
  AuthBasicProvider socache dbd

  # Also required for caching: tell the cache to cache dbd lookups!
  AuthnCacheProvideFor dbd
  AuthnCacheContext my-server

  # mod_authz_core configuration
  Require valid-user

  # mod_authn_dbd SQL query to authenticate a user
  AuthDBDUserPWQuery "SELECT password FROM authn WHERE user = %s"
</Directory>



Exposing Login Information


Whenever a query is made to the database server, all
column values in the first row returned by the query are placed in the
environment, using environment variables with the prefix "AUTHENTICATE_".

If a database query for example returned the username, full name
and telephone number of a user, a CGI program will have access to
this information without the need to make a second independent database
query to gather this additional information.
This has the potential to dramatically simplify the coding and
configuration required in some web applications.



AuthDBDUserPWQuery Directive

Description:SQL query to look up a password for a user
Syntax:AuthDBDUserPWQuery query
Context:directory
Status:Extension
Module:mod_authn_dbd

    The AuthDBDUserPWQuery specifies an
    SQL query to look up a password for a specified user.  The user's ID
    will be passed as a single string parameter when the SQL query is
    executed.  It may be referenced within the query statement using
    a %s format specifier.
    AuthDBDUserPWQuery "SELECT password FROM authn WHERE user = %s"

    The first column value of the first row returned by the query
    statement should be a string containing the encrypted password.
    Subsequent rows will be ignored.  If no rows are returned, the user
    will not be authenticated through mod_authn_dbd.
    Any additional column values in the first row returned by
    the query statement will be stored as environment variables with
    names of the form AUTHENTICATE_COLUMN.
    
    The encrypted password format depends on which authentication
    frontend (e.g. mod_auth_basic or
    mod_auth_digest) is being used.  See Password Formats for
    more information.



AuthDBDUserRealmQuery Directive

Description:SQL query to look up a password hash for a user and realm.

Syntax:AuthDBDUserRealmQuery query
Context:directory
Status:Extension
Module:mod_authn_dbd

    The AuthDBDUserRealmQuery specifies an
    SQL query to look up a password for a specified user and realm in a
    digest authentication process.
    The user's ID and the realm, in that order, will be passed as string
    parameters when the SQL query is executed.  They may be referenced
    within the query statement using %s format specifiers.
    AuthDBDUserRealmQuery "SELECT password FROM authn WHERE user = %s AND realm = %s"

    The first column value of the first row returned by the query
    statement should be a string containing the encrypted password.
    Subsequent rows will be ignored.  If no rows are returned, the user
    will not be authenticated through mod_authn_dbd.
    Any additional column values in the first row returned by
    the query statement will be stored as environment variables with
    names of the form AUTHENTICATE_COLUMN.
    
    The encrypted password format depends on which authentication
    frontend (e.g. mod_auth_basic or
    mod_auth_digest) is being used.  See Password Formats for
    more information.




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